Answer:
Ladders or wrecking the main door down with tree like devices
Explanation:
People before used to burn or "blast" the doors of an empire down by choping a tree down and leaving only the trunk, then they put wheels wooden wheels below them to wreck the doors down. Or they could infiltrate the empire by charging to the main walls and taking archers down with bows, then take the walls down with catapults, and finally infiltrate the city and fight with sword and shield.
Hope this helps
